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A while back I decided to switch to an SSD for my OS storage for the speed boost. At the same time I realised that the majority of time it takes for my PC to start up, was due to hanging PRIOR to loading the OS. Over a minute in fact.

Apparently, my keyboard and/or mouse were trumping the boot order somehow. In any case, disabling USB Legacy Support fixed this issue, it booted nearly instantly after that.

Fast forward to now, I've decided to get into Linux and dual boot. Unfortunately, due to disabling the aforementioned, my wireless keyboard is not detected at boot. This means I can't make a choice in the GRUB menu when it comes up.

This is not optimal. :(

I verified the USB issue by re-enabling legacy support, at which point I could use my keyboard to select an option. (It also caused the hang before loading the OS to return.)

Switching to a 3.0 port, with all the 3.0 stuff enabled and 2.0 legacy support disabled, did nothing. Unable to use the keyboard, boot was fast.

I'm sensing that, if there is a solution to this conflict, it lies in resolving the boot issue without disabling USB Legacy Support.

Any suggestions appreciated. :)

Motherboard: ASUS M5A97. BIOS: American Megatrends Inc. Version: 1605. Keyboard: Logitech K750.

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I would first update the BIOS. I would then report the problem to ASUS. It might not be possible to resolve legacy usb is a known problem with newer motherboards and UEFI in general. As for the reason it does not work without it being enabled:… – Ramhound Jun 18 '13 at 20:10
@Ramhound - BIOS is up to date, as far as I can tell from the ASUS website, version 1605 is the latest. I did update from 900 and something, directly to 1605 but it surely would include all previous fixes. I'll contact ASUS. Both mouse and keyboard can cause the hang independently, but I haven't tried them both in the 3.0 ports. I feel I'm scraping the bottom of the barrel with that one, but I have no idea how to proceed otherwise. – Scott Oliver Jun 19 '13 at 8:51
Do you have a different USB keyboard you can try? I am thinking your problems come from it being a USB 2.0 device and not a native USB 3.0 device. Does your motherboard and CPU support native USB 3.0. Basically asking if its z67/z87/... – Ramhound Jun 19 '13 at 11:35
@Ramhound - Solution Get! See my answer for details. :D – Scott Oliver Jun 19 '13 at 20:40

Looks like I was right about the mouse. ^__^

Having already discovered (during the SSD upgrade) that both my mouse and keyboard could independently cause the hanging issue at start up, I set about trying different ports, including the two USB 3.0 ports (given that there are separate settings for 2.0 and 3.0 ports in the BIOS, I considered that this may offer a solution).

Which it kinda did. While I doubt any changes I made to the 3.0 settings mattered (I turned on battery charging :/ I should turn that off...) having both my mouse and wireless keyboard dongle plugged into the USB 3.0 ports NOT the 2.0 ports, and then re-enabling USB Legacy Support has resulted in a solution!

It seems whatever was causing the hanging, was some combination of USB keyboard and/or mouse plugged into USB 2.0 ports, while having USB Legacy Support enabled. When the keyboard and/or mouse are plugged into the 3.0 ports while the setting is enabled, this issue goes away and both devices can be discoverd and used during boot, BIOS and GRUB. NOTE FOR GRUB: Apparently any mouse input is always interpreted as scroll really fast and select Memtest. :/

Anyhoo, if anything similar happens to anyone else, consider testing with each of your USB peripherals to discover the cause of the hanging. Then see if there are other ports you can switch to, before disabling USB Legacy Support.

Moral of the story there.

share|improve this answer
This is likely because your motherboard/CPU has native USB 3.0 support which means it can boot to a USB 3.0 device. It could simply be a bug with your motherboard. Using your 3.0 ports on your devices you need before you access your operating system is likely a good thing anyways. – Ramhound Jun 20 '13 at 11:31

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